SEPARATOR FOR INSULATING ADJACENT BATTERY CELLS, AND POWER SOURCE DEVICE PROVIDED WITH SAME

To achieve both formability and heat insulating properties, separator according to an aspect of the present invention insulates adjacent battery cells. Separator includes heat insulation sheet including a fiber material and a heat insulation material including higher heat insulating properties than the fiber material, and formed member including higher shape stability than the heat insulation sheet. This enables shape of heat insulation sheet including high flexibility to be maintained using formed member formed into a predetermined shape.